PHYSICAL ACTIVITY ASSESSMENT TOOLS IN MONITORING PHYSICAL ACTIVITY: THE GLOBAL PHYSICAL ACTIVITY QUESTIONNAIRE (GPAQ), THE INTERNATIONAL PHYSICAL ACTIVITY QUESTIONNAIRE (IPAQ) OR ACCELEROMETERS - CHOOSING THE BEST TOOLS

Assessing physical activity in epidemiological studies is a severe challenge for researchers, whose overriding aim is to obtain accurate, truthful and reliable data on the level of physical activity in different population groups. Presently, both objective and subjective measurement methods are used. The tools used in objective methods are usually pedometers and accelerometers, while in subjective are used questionnaires conducted and run either as self-reported or by a trained interviewer. At the end of the 1990s, experts in the field of epidemiology of physical activity began developing normalised and standardised tools for subjective assessment of physical activity. After several years of experience, we know that well-chosen and properly validated tools used in the testing process conducted in accordance with recommended standards are a prerequisite for obtaining accurate, truthful and reliable data. Although there are over 90 different questionnaires for physical activity, the two most commonly used are the International Physical Activity Questionnaire (IPAQ) and the Global Physical Activity Questionnaire (GPAQ). On the other hand, objective tools such as pedometers or accelerometers are used more and more frequently in cohort and experimental studies, but also those concerning populations. The article reviews the literature on the criteria of selection and usage of these popular tools. The advantages and disadvantages of each of them and the results of the most important comparative validation studies are discussed.